That sounds horrible! I guess you've made sure it is all hooked up with tight connections? Have you tried putting some shelf liner foamy stuff under it?
Is the pump next to a sidewall? also is the foam head reaching the top?
how deep is the water
I'm on dial-up so I didn't watch tape. Did you check your pin wheel, shaft ok, mag and housing smooth, no gravel snails? Did it have proper, not worn out seat on both ends of shaft. Some, such as ASM Skimmer are kinda loud, high vibration pumps, I had a Eurro-Reef with a Sedra pump that sounded like a sonic bath, it was normal for that pump
Is it a new skimmer? I had the same noise with my new octopus, it was very annoying, I was just about to send the pump in for replacement and then it just stopped the loud noise all of a sudden.It was wierd cause everything was hooked up right and there was no debris in it all. It has been almost a year now and its still working great. What kind of pump is it? Is the otp?
It was a little over 2 weeks, maybe something is wrong with the new OTP pump design. My main concern is that whatever was causing the sound might have shortened the life of my pump. You should get the pump replaced, thats what i should have done but I had no backup skimmer, my bio-load is HUGE and I feed ALOT, so I didnt want to run without one.